I'm a bit skeptical here. I can understand handling EPERM, but EFAULT would generally imply an error on *our* side, not something that should be silently ignored.

[2017-10-21 18:11 UTC] security at paragonie dot com

EPERM is not supposed to be returned by this system call. That means that QNAP is behaving weirdly and the problem should be fixed on their side.
If a QNAP-specific workaround is desired, first we will need to ensure it's only ever employed on QNAP kernels. Is there a way to detect them at compile-time?